Heaven : Are there bright lights and angels? Can you surf? Everybody's wondering what gives in the afterlife.

In heaven, Peter Kreeft found himself in an immense cathedral, surrounded by thousands of souls dressed in white robes. Suddenly, a door swung open and voices whispered, "Hush! Here he comes." Kreeft, assuming it was the Lord, watched as "in stumbled a fat, disheveled, bewildered German man." It was Ludwig van Beethoven--and the robed souls welcomed him into Paradise by singing the "Ode to Joy" from his Ninth Symphony.

Then Kreeft woke up.

But even though this visit was just a dream, Kreeft knows the place better than most people. A philosophy professor at Boston College and author of two books on heaven, he is one of the latest in a long line of afterlife explorers.

For centuries, heaven has been imagined by poets, debated by theologians and mapped out by visionaries who claim to have been there.

What they describe is a realm of floating lights, colors that can be tasted, and creatures with flesh and bone fashioned from emeralds. It is a dimension where time runs backward and forward, water turns into glass and--for Mormons--dead souls rule their own planets.

Today, there is a new surge of speculation about what lies beyond the grave.

The graying of baby boomers, the passing of their parents and the specter of AIDS are "making people think about death," says religion historian Colleen McDannell. "People who aren't supposed to be dying are dying."

Books with such titles as "Embraced by the Light" and "Life After Life" have bobbed to the top of bestseller charts. Talk shows buzz with guests recounting near-death experiences.

And philosophers grapple with such questions as, "If heaven isn't in outer space, why did Jesus ascend skyward to get there?" "Will Paradise get boring?" and even, "Is there surfing in the afterlife?"

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For a place that's supposed to be eternal, the afterlife sure has changed a lot over the years.

Ancient Jews, who sometimes tried to contact the dead through seances, believed that all spirits went to a dark, silent underworld cave called Sheol, says McDannell, a University of Utah professor who co-authored "Heaven: A History" (Yale University Press, 1988).

It wasn't until six centuries before Christ that the concepts of heaven and hell began forming. That's when two Jerusalem poets composed Psalms 49 and 73, introducing the idea that good people would get preferential treatment after death.

But details were scarce. The original heaven was thought to be an eternal study hall, says Richard Hecht, a religious studies professor at UC Santa Barbara. The righteous sat at desks, learning from God.

Then Christianity arrived--and the concept of heaven lurched through a series of transformations.

In the book of Revelation, for instance, the celestial kingdom featured lightning, a glass ocean and six-winged, multi-eyed animals guarding the Almighty's throne.

By the end of the 2nd Century, it had metamorphosed into a land of free-flowing wine, banquets and super-fertile humans giving birth to platoons of children. That, in turn, gave way to St. Augustine's mysterious vision.

While sitting in a villa in Italy, Augustine wrote, he and his mother were transported to Paradise, an experience so emotionally intense that she lost all desire for earthly pleasures. "The (vision) had severed her from worldly attachments as well as loosening her soul from her body," McDannell and co-author Bernhard Lang write. "Within a fortnight, (she) was dead." Later images of heaven reflected cultural trends, the authors say. As cities came to prominence in the 12th and 13th centuries, heaven took on an urban look, with buildings and streets made of jasper, gold and pearls.

The Renaissance produced a sensuous afterlife of fragrant gardens, angelic melodies and the ability to kiss another person from thousands of miles away "with the same pleasure as when the lips actually meet," they write.

From there, concepts of Paradise have seesawed between austere, God-centered eternities and earthly landscapes full of activity. The latter became especially popular after a middle-aged Swedish mining official's alleged visit to the next world.

In 1744, the story goes, Emanuel Swedenborg encountered a supernatural force that hurled him to the ground, forced him to pray and then took him to the land of the dead. What he saw--parks, cities, strange weddings and "garments that shown like flaming light"--started an avalanche of afterlife speculation, McDannell says.

In the United States, more than 50 books about heaven were published between 1830 and 1875. And by the turn of the century, the increasingly modern hereafter was equipped with theaters, time-travel machines, amusement parks, suburbs and schools.

Even Mark Twain jumped into the debate, slamming one account--which envisioned departed souls playing pianos, eating gingersnaps and living in Victorian cottages--as "a mean little 10-cent heaven about the size of Rhode Island."

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Today, although nearly 80% of Americans say they believe in heaven, the old imagery has lost much of its allure.